Final

— July 2, 2015 1 

## Significant New Alternatives Policy Program

Refrigeration and Air Conditioning Sector
Risk Screen on Substitutes in Refrigerated Transport
Substitute: R

- 513A ( Opteon® XP10 )

This risk screen does not contain Clean Air Act (CAA) Confidential Business Information (CBI) and, therefore, may be disclosed to the public.



### 1. INTRODUCTION
Ozone

- depleting substances (ODS) are being phased out of production in response to a series of diplomatic
a nd legislative efforts that have taken place over the past two decade s , including the Montreal Protocol and the Clean Air Act Amendments of 1990 (CAAA). The U.S. Environmental Protection Agency (EPA), as authorized by Section 612 of the CAAA, administers the Significant New Alternatives Policy (SNAP) Program, which identifies acceptable and unacceptable substitutes for ODS in specific end

- uses based on assessment of their health and environmental impacts. EPA’s decision on the acceptability of a substitute is based on the findings of a screening assessment of potential human health and environmental risks posed by the substitute in specific applications. EPA has already screened a large number of substitutes in many end

- use applications within al l of the major ODS

using sectors including : refrigeration and air conditioning, solvent cleaning, foam blowing, aerosols, fire suppression, adhesives, coatings and inks, and sterilization. The results of these risk screens are presented in a series of Background Documents that are available in EPA' s docket. The purpose of this risk screen is to supplement EPA’s Background Document on the refrigeration and air conditioning sector (EPA 1994) (hereinafter referred to as the Background Document) . This risk screen eval uates the potential use of R

- 513A (a lso known as Opteon® XP10) as a substitute in the refrigerated transport end

- use, specifically in trucks and trailers

. Table 1 presents the composition of the proposed substitute. Table 1 . Composition of R

- 513 A and Potential Impurities
Constituent Chemical Formula CAS Number Concentration (Weight Percent) 2,3,3,3

- Tetrafluoropropene (HFO

- 1234yf) CH 2 CFCF 3 754

- 12

- 1 ≤ 56 % 1,1,1,2

- Tetrafluoroethane (HFC

- 134a) CF 3 CH 2 F 811

- 97

- 2 ≤ 44 % Potential Impurities

Section 2 summarizes the results of the risk screen for the proposed substitute blend listed in Table 1 . The remainder of the risk screen is organized into the following sections:

• Section 3 : Atmospheric Assessment

• Section 4 : Volatile Organic Compound Assessment

• Section 5 : Discussion of End

- Use Scenario s Modeled

• S ection 6 : Potential Health Effects

• Section 7 : Flammability Assessment

• Section 8 : Asphyxiation Assessment

• Section 9 : End

- Use Exposure AssessmentFinal

— July 2, 2015 2 • Section 10 : Occupational Exposure Assessment

• Section 11 : General Population Exposure Assessment

• Section 12 : References


### 2. SUMMARY OF RESULTS
R

- 513A is recommended for SNAP approval for the refrigerated transport end

- use, specifically in trucks and trailers

. E PA's risk screen indicates that the use of the proposed substitute will be less harmful to the atmosphere than the continued use of ODS and other commonly used refrigerants , as it is less harmful to the ozone layer, has lower climate impact, and a shorter atmospheric lifetime

. T he components of R

- 513A
are not subject to volatile organic compound (VOC) regulations under the CAA (40 CFR 51.100(s)) , so environmental impact from the release of these substances is not a concern

. In addition, because R

- 513A is considered to be nonflammable, the proposed substitute is not expected to present a flammability concern. It is expected that the manufacturer’s safety data sheet (SDS) for R

- 513A and good manufacturing practices will be adhered to , and appropriate safety and personal protective equipment (PPE) (e.g., protective gloves, tightly sealed goggles, protective work clothing, and suitable respiratory protection in case of leakage or insufficient ventilation) consistent with Occupational Safety and Health Administration (OSHA) guidelines will be used during manufacture, servicing, and disposal of refrigerated transport units using R

- 513A

. In addition, it is expected that leak detecto rs will be installed inside refrigerated transport containers and container doors will be open during end

- use to prevent significant exposure to R

- 513A in the case of catastrophic leakage. Because refrigerated transport units are to be installed in locatio ns with adequate space and/or ventilation (i.e. , outdoors) in accordance with EPA recommendations and the equipment maintenance manual s for R

- 513A in the refrigerated transport end

- use , significant toxicity risk to consumers is also unlikely. Additional s afeguards, including specified refrigerant concentration limits (RCL) of R

- 513A and its components, are also provided by adherence to industry standards including American Society of Heating, Refrigerating and Air

- Conditioning Engineers (ASHRAE) Standards 15, 1 34, 2 and 62. 3



### 3. ATMOSPHERIC ASSESSMENT This section presents an assessment of the potential risks to atmospheric integrity posed by the use of R

513 A in refrigerated transport. The ozone depletion potential ( ODP ) , global warming potential ( GWP ) , and atmospheric lifetime (ALT) of the proposed substitute are presented in Table 2

. The proposed substitute is substantially less harmful to the oz one layer, has lower climate impact, and a shorter ALT when compared to CFC

- 12 , R

- 502 , and HCFC

- 22

. In addition, R

- 513 A also has lower climate impact and a shorter ALT than those predicted for other substitutes examined in the Background Document , as well as commonly utilized refrigerants in refrigerated transport, HFC

- 134a, R

- 404A , R

507A, and R

- 407C . Thus, EP A believes that the use of R

- 513 A would result in substantially less harm to the climate and ozone layer than the continued use of ODS and o ther commonly used refrigerants

.

1 Safety Standard for Refrigeration Systems ASHRAE Standard 15 establishes safeguards for life, limb, health, and property and prescribes safety requirements. 2 Designation and Safety Classification of Refrigerants ASHRAE Standard 34 e stablishes a uniform system for assigning reference numbers, safety classifications, and refrigerant concentration limits to refrigerants. Safety classifications based on toxic ity and flammability data are included. 3 Ventilation for Acceptable Indoor Air Quality ASHRAE Standard 62 establishes minimum ventilation rates and other measures intended to provide indoor air quality that is acceptable to human occupants and that minimizes adverse health effects

.Final

— July 2, 2015 3 Table 2 . Atmospheric Impacts of R

- 513A Components Compared to Other Refrigerants Used in Refrigerated Transport Refrigerant Ozone Depleting Potential ( ODP ) a Global Warming Potential ( GWP ) b Atmospheric Lifetime in Years ( ALT ) b R

- 513A 0 631 NA c Individual Components HFC

- 134a 0 1,430 14 HFO

- 1234yf 0 4 d 11 days d CFC

- 12 0.82 10,900 100 b R

- 502 e 0. 2 4,650 NA f HCFC

- 22 0.13 1,810 12 a R

- 404A g 0 3,922 NA h R

- 507 A i 0 3,985 NA j R

- 407C k 0 1,774 NA l

a WMO 2010 Scientific Assessment Report (2011) b IPCC 4 th Assessment Report (Forster et al. 2007)

c Atmospheric lifetimes are not given for blends, because the components separate in the atmosphere. The ALT for HFC

- 134a is 14 years and the ALT for HFO

- 1234 yf is 11 days (IPCC 4 th Assessment Report [Forster et al. 2007], Papadimitriou et al

. (2007) ). d Papadimitriou et al

. (2007)

e R

- 502 is a blend consisting of HCFC

- 22 (49%) and CFC

- 115 (51%)

. f Atmospheric lifetimes are not given for blends, because the components separate in the atmosphere. The ALT for HCFC

- 22 is 12 years and the ALT for CFC

- 115 is 1,700 years (IPCC 4 th Assessment Report [Forster et al. 2007]). g R

- 404A is a blend consisting of HFC

- 143a (52%), HFC

- 125 (44%) and HFC

- 134a (4%). h Atmospheric lifetimes are not given for blends, because the components separate in the atmosphere. The ALT for HFC

- 143a is 52 years, the ALT for HFC

- 125 is 29 years, and t he ALT for HFC

- 134a is 14 years ( IPCC 4 th Assessment Report [Forster et al. 2007]). i R

- 507A is a blend consisting of HFC

- 125 (50%) and HFC

- 143a (50%). j Atmospheric lifetimes are not given for blends, because the components separate in the atmosphere. The ALT for HFC

- 125 is 29 years and ALT for HFC

- 143a is 52 years (IPCC 4 th Assessment Report [Forster et al. 2007]). k R

- 407C is a blend consisting of HFC

- 32 (29%), HFC

- 125 (25%) and HFC

- 134a (52%). l Atmospheric lifetimes are not given for blends, because the components separate in the atmo sphere. The ALT for HFC

- 32 is 4.9 years, the ALT for HFC

- 125 is 29 years, and t he ALT for HFC

- 134a is 14 years (IPCC 4 th Assessment Report [Forster et al. 2007]).


### 4. VOLATILE ORGANIC COMPOUND ASSESSMENT The components of R

- 513A, HFC

- 134a and HFO

- 1234yf , are exempt from the definition of VOCs under CAA regulations (40 CFR 51.100(s))

. Therefore, VOC impacts from the release of R

- 513A are not a
concern.


### 5

. DISCUSSION OF END

- USE SCENARIOS MODELED R

- 513A has been proposed for use in refrigerated transport uni ts. As provided by the submitter, the typical and maximum charge sizes for R

- 513A in trucks and trailers are listed in Table 3. Table 3 . Typical and Maximum Charge Sizes for Various R

- 513 A End

- Uses and Applications

End

- Use Application Typical Charge Size (kg) Maximum Charge Size (kg) Refrigerated

Transport Trucks 2 5 Trailers 7 15
To evaluate potential end

- use exposures for R

- 513 A in refrigerated transport units , this risk screen examines a scenario in which a catastrophic leak of refrigerant occurs while personnel are inside the refrigerated transport container and the doors to the container are closed . A more reasonable worst

- case scenario for this assessment would consider the catastrophic leak of refrigera nt occurring while the container doors are open , because EPA expects the refrigerated container door s to be open while personnel are present inside the container at end

- use (e.g., during loading and unloading of refrigerated goods)

. However, the limitations of the box model used for this assessment do not allow consideration of thisFinal

— July 2, 2015 4 scenario; calculating the concentration of R

- 513A in the container as it exchanges with the warm, outside air through the open door would require more c omplex computational fluid dynamic s modeling. Given these limitations, the risk screen evaluates a more unlikely scenario, in which it is assumed that the full charge of the refrigerated transport unit is emitted over the course of one minute into the ref rigerated container with the door closed. Although R

- 513A is denser than air, a vertical concentration gradient is not assumed, because when the full charge is released, the presence of ventilation and the high pressure operating conditions of the refriger ant are expected to disperse the proposed substitute evenly and immediately throughout the refrigerated transport container. It i s assumed that an individual is present at the start of the leak and remains in the container until the charge is completely re leased. Furthermore, this risk screen evaluates a refrigerated transport unit with a ventilation rate of 25 m 3 /hr, a lower ventilation rate appropriate for less perishable produce (perishable items require a higher ventilation rate up to 60 m 3 /hr) (Brecht et. al 2000). Hence, based on suggested ventilation rates for refrigerated transport units for various types of produce, this analysis conservatively assumes a ventilation rate of 25
m 3 /hr. 4 Table 4 details the end

- use modeling assumptions used in Sections 8 and 9

. Table 4

. End

- Use Scenario Model Assumptions
Parameter Assumptions (Trucks) Assumptions (Trailers) Refrigerated Transport Container Trucks Trailers Charge Size (kg) 2; 5 7; 15 Length of Release (minutes) 1 1 Container Size (volume

- m 3 ) 78 (2, 76 0 ft 3 ) a 100 (3,530 ft 3 ) b Room Ventilation (m 3 /hr) 25 25 Vertical Concentration Gradient No No

a Specific information was not availabl e regarding the sizes of the refrigerated transport trucks

. Thus, a standard 26 ft. ( 7.9 m) refrigerated truck was used for this scenario, with a height of 12. 5 ft ( 3.8 m ) and a width of 8.5 ft (2.6 m) ( C.H. Robinson
, 2012 )

. b According to the United Nations Environmental Programme (UNEP), trailers have box volumes of approximately 100 m

3 (UNEP 2010). EPA recognizes that refrigerated transport units may be placed in a variety of containers with different sizes and ventilation rates. When units are installed in smaller containers , there is a higher risk for asphyxiation or significant exposure

. To address th is variability in container volumes and charge sizes for refrigerated transport units , this risk screen incorporates thresh old analyses in addition to the worst

- case scenario modeling . The threshold analyses are performed in order to determine the container size and charge size r equirements that ensure that th e use of R

- 513A in refrigerated transport does not present risk to end

- users or servicing technicians

. 

### 6

. POTENTIAL HEALTH EFFECTS To assess potential health risks from exposure to the proposed substitute in refrigerated transport end

- uses , EPA identified the relevant toxicity threshold values for comparison to modeled ex posure concentrations for different scenarios. According to ASHRAE Standard 34

- 2013, R

- 513A is listed under safety group A1 with a RCL of 72,000 ppm (ASHRAE 2015) . ASHRAE 34 RCLs are intended to reduce the risks of acute toxicity, asphyxiation, and flammab ility hazards in normally occupied, enclosed spaces during refrigerant
use , and protect end

- users from the potential dangers of a catastrophic leak from a refrigeration unit (ASHRAE 2010b). ASHRAE Standard 15 implements the aforementioned standard, requiring that “the concentration of refrigerant in an enclosed space following a complete discharge of a high

- probability system shall not exceed the RCL” (ASHRAE 2010a). As such, this risk screen references the proposed RCL for R

- 513A in addition to the hypoxia no observed adverse effect level (NOAEL) and exposure

4 Ventilation rates range from 0 to 60 m 3 /hr depend ing on the type of good that is transported (Hamburg Süd 2010).Final

— July 2, 2015 5 limits, as an additional, conservative limit to ensure that significant asphyxiation and end

- use exposure risks, respec tively, do not occur. For the occupational exposure analysis, potential risks from chronic and acute worker exposure were evaluated by comparing exposure concentrations to available occupational exposure limits. Potential risks of chronic worker exposur e were evaluated using workplace guidance levels (WGL) , such as Workplace Environmental Exposure Levels (WEELs)

. Risks from potential short

- term consumer exposures were evaluated by comparing exposure concentrations to emergency guidance levels (EGL). In t he absence of
an established short

- term exposure limit (STEL), acute exposure guideline level (AEGL), or emergency response planning guideline (ERPG) for R

- 513A , potential short

- term end

- use exposures were evaluated on a component basis (i.e., HFC

- 134a and HFO

- 1234 yf ). Table 5 lists the relevant toxicity limits for R

513A and its component s , and is followed by Table 6 , which provides an explanation of each toxicity limit

. EPA’s approach for identifying or developing these values is discussed in Chapter 3 of the Background Document.

Table 5

. Exposure Limits of R

- 513A Components
R

- 513A Component WGL (Long

- term Exposure)

ppm EGL (Short

- term Exposure) p pm Refrigerant Concentration Limit (RCL) ppm R

- 513 A 65 3 (8

- hour AEL ) 1,960 (15

- min STEL) a 72,000 Individual Components
HFC

- 134a 1 ,000 ( 8

- hour WEEL ) 8,000 (10

- min AEGL

- 1) 8,0 00 (30

- min AEGL

- 1) 50,000 HFO

- 1234yf 500 ( 8

- hour WEEL ) 1
, 500 ( 15

- min STEL ) b 10 1 ,000 c

a Neither the American Conference of Governmental Industrial Hygienists ( ACGIH ) nor the American Industrial Hygiene Association ( AIHA ) recommend ceiling or short term exposure limits for the blend R

- 513 A. A STEL for R

- 513A of 1, 9 60 ppm was developed by EPA b ased on the 65

3 ppm AEL value. The STEL was estimated as three to five times the acceptable exposure limit ( AEL ) , which is an established method of estimating a short

- term exposure limit by ACGIH . [STEL] = [AEL] x 3 = 653 ppm x 3 ≈ 1,9 60 ppm b Neither ACGIH nor AIHA recommend ceiling or short term exposure limits for HFO

- 1234 yf

. A STEL for HFO

- 1234 yf of 1
, 500 ppm was developed by EPA based on the 500 ppm WE EL value. The STEL was estimated as three to five times the AEL, which is an established method of estimating a short

- term exposure limit by ACGIH . [STEL] = [AEL] x 3 = 500 ppm x 3 ≈ 1
, 500 ppm
c Although an RCL has not been proposed for HFO

- 1234 yf

, the recommended ATEL for HFO

- 1234 yf is 10 1 ,000 ppm ( DuPont Fluoroproducts 20

14

).
Table 6 . Explanation of Exposure Limit

- Related Terminology a Organization Definition OSHA Occupational Safety and Health Administration NIOSH National Institute for Occupational Safety and Health ACGIH American Conference of Governmental Industrial Hygienists AIHA American Industrial Hygiene Association OARS Occupational Alliance for Risk Science Exposure Limit Definition Explanation Short

- Term Exposure RCL Refrigerant Concentration Limit The RCL for a refrigerant is intended to reduce the risks of acute toxicity, asphyxiation, and flammability hazards in normally occupied, enclosed spaces. The RCL for each refrigerant is the lowest of the Acute

- Toxicity Exposure Limit (ATEL), Oxygen Deprivation Limit (ODL), and Flammable Concentration Limit (FCL). Determination assumes full vaporization with no removal by ventilation, dissolution, reaction, or decomposition and complete mixing of refrigerant in the space to which it is released. ATEL Acute Toxicity Exposure Limit The ATEL is the refrigerant concentration limit intended to reduce the risks of acute toxicity hazards in normally occupied, enclosed spaces according to ASHRAE Standard 34. The ATEL includes consideration of mortality, cardi ac sensitization, anesthetic or central nervous systemFinal

— July 2, 2015 6 effects and other escape impairing effects and permanent injury. The ATEL is similar to the Immediately Dangerous to Life or Health (IDLH) concentrations set by NIOSH. STEL Short

- Term Exposure Limit A 15

- minute time

- weighted average (TWA) exposure that should not be exceeded during a workday, even if the 8

- hour TWA is within the threshold limit value

- time weighted average ( TLV

– TWA ) , set by ACGIH.

AEGL b,c Acute Exposure Guideline Level 1 AEGL

- 1 is the airborne concentration (expressed as ppm or mg/m 3 ) of a substance above which it is predicted that the general population, including susceptible individuals, could experience notable discomfort, irritation, or certain asymptomatic nonsensory effects. However, the effects are not disabling and are transient and reversible upon cessation of exposure. Acute Exposure Guideline Level 2 AEGL

- 2 is the airborne concentration (expressed as ppm or mg/m 3 ) of a substance above which it is predicted that the general population, including susceptible individuals, could experience irreversible or other serious, long

- lasting adverse health effects or an impaired ability to escape. Acute Exposure Guideline Level 3 AEGL

- 3 is the airborne concentration (expressed as ppm or mg/m 3 ) of a substance above which it is predicted that the general population, including susceptible individuals, could experience life

- threatening health effects or death. Long

- Term Exposure PEL Permissible Exposure Limit This is an 8

- hour TWA exposure limit set by OSHA. AEL Acceptable Exposure Limit The maximum 8

- hour TWA at which a worker can be exposed regularly without adverse effects. WEEL Workplace Environmental Exposure Level Developed by OARS for to protect healthy workers against acute and chronic health effects, this limit is based on repeated daily exposures over a working lifetime and averaged over an 8

- hour workday. TLV

- TWA Threshold Limit Value

– Time

Weighted Average The TWA concentration for a conventional 8

- hour workday and a 40

- hour workweek, to which it is believed th at nearly all workers may be repeatedly exposed, day after day, for a working lifetime without adverse effect according to ACGIH.

a All information in this table taken from EPA (1994) except where otherwise noted. b EPA (2012)

c A pplicable to emergency exposure periods ranging from 10 minutes to 8 hours. According to the SDS, exposure to R

- 513A may be hazardous if inhalation, skin contact, or eye contact with the proposed substitute occurs. The most likely pathway of exposure is through inhalation. R

- 51 3 A can cause symptoms of asphyxiation when present in concentrations high enough to significantly lower oxygen concentrations below 19.5 percent by volume, such as headaches, ringing in ears, dizziness, drowsiness, nausea, vomiting, depression of all sense s, and also unconsciousness. Under some circumstances of over

- exposure (i.e., oxygen levels fall below 6 percent by volume), death may occur. If inhaled, R

- 513A can cause symptoms such as light

- headedness, dizziness, confusion, incoordination, drowsiness, unconsciousness, and anesthetic effects. Excessive inhalation of R

- 513A may also result in an irregular heartbeat or death, due to cardiac effects. If R

- 513 A is inhaled, person(s) should be immediately removed from the contaminated space and exposed to f resh air. In accordance with the SDS, EPA further recommends that if breathing is difficult or irregular , person(s) should be given oxygen, provided a qualified operator is present, a nd medical attention be sought. Exposures of R

- 513A to the skin may cause frostbite. In the case of dermal exposure, the SDS for R

- 513 A recommends that person(s) immediately wash the affected area with water and remove all contaminated clothing; if frostbite occurs, bathe (not rub) the affected area with lukewarm, not hot, wate r. If water is not available, cover the affecte d area with a clean, soft cloth , and seek medical attentio nFinal

— July 2, 2015 7 immediately. Exposures of R

- 513 A to the eyes could cause eye irritation. In case of ocular exposure, the SD S for R

- 513A recommends that person(s) imm ediately flush the eyes, including under the eyelids, with copious amounts of water for 15 minutes. EPA’s review of the human health impacts of this proposed substitute is contained in the public docket for this decision. These risks and procedures after exposure are similar for other common refrigerants. The p otential health effects of R

- 513A can be minimized by following the exposure guidelines , and ventilation and PPE recommendation s outlined in the SDS for R

- 513A and this risk screen.



### 7

. FLAMMABILITY A SSESSMENT
R

- 513A is classified as an A1 refrigerant by ASHRAE , and is considered to be nonflammable ( DuPont Fluoroproducts 2014 ; ASHRAE 2015 ). Based on this classification, manufacture, servicing, and use of R

513A is not expected to present a flammability risk in the refrigerated transport end

- use

. 

### 8

. ASPHYXIATION ASSESSMENT The risk of asphyxiation for the reasonable worst

- case scenario described in Section 5 was investigated for R

- 513A . In this section, risk of asphyxiation is assessed in three ways: 1) modeling the oxygen concentration under the maximum charge size and container size specified in the worst

- case scenario, 2) performing a threshold analysis of the minimum charge size needed to cause an asphyxiation risk in the room size specified in the worst

- case scenario , and 3) performing a threshold analysis of the minimum container size needed to cause an asphyxiation risk with the maximum charge size specified in the worst

case scenario. This analysis does not consider ventilation or conditions that are likely to occur that would increase oxygen levels to which individuals would be exposed, such as open container doors, which allow air to flow in and out. As specified in Section 5, the worst

- case scenario does not assume a vertical concentration grad ient. If the proposed substitute passes the screening analysis with these restrictive assumptions in place, it can be reasonably assumed that no risks of asphyxiation will be pres ent under real

world conditions. The results of the asphyxiation assessment a re summarized in Table 7 below. Table 7 . Asphyxiation Assessment a Refrigerated Transport Application Scenario Charge Size ( k

g) Effective Container Size (m

3 ) Percent Oxygen Concentration b Trucks Scenario 1a : Maximum Charge Size 5 78 (2,760 ft 3 ) 21 % Trailers Scenario 1 b : Maximum Charge Size 15 100 (3,530 ft 3 ) 20 % Trucks Threshold Analysis 1a: Charge Size 1 50 78 (2,760 ft 3 )
12 % Trailers Threshold Analysis 1b: Charge Size 19 0 100 (3,530 ft 3 ) Trucks Threshold Analysis 2a: Container Size 5 2.6 ( 93 ft 3 ) Trailers Threshold Analysis 2b: Container Size 15 7.9 (280 ft 3 ) Bold font indicates modeling results.

a Cells highlighted in green are the scenarios in which the charge and container sizes evaluated in this risk screen are acceptable according to the threshold analysis or the scenarios with acceptable oxygen concentrations, given various modeling assumption options. b The typical concentration of oxygen in air is considered to be 21 p ercent (Mackenzie & Mackenzie 1995). In order for a risk of asphyxiation to occur, the normal concentration of oxygen in air (21 percent) must be reduced to 12 percent. 5 Based on the worst

- case scenario modeling for R

- 513A , a release of the maximum charge sizes indicated by the submitter in trucks and trailers (i.e., 5 kg and 15 kg, respectively) does not present a significant risk of asphyxiation. This modeling does not take into account any ventilation which is likely to occur, such as open container doors that allow air to flow in and out, as mentioned above. Thus, the actual asphyxiation risk to personnel is likely to be even smaller than modeled.

5 Twelve percent oxygen in air is the NOAEL for hypoxia (ICF 1997).Final

— July 2, 2015 8 For the asphyxiation threshold analyses shown in Table 7 , the conditions at which an asphyxiation concern would exist were determined.

• Within a container size of 78 m 3 ( 2, 760 ft 3 ), as shown under Threshold Analysis 1a, the charge size of the R

- 513A refr igerated truck unit would have to be at least 150 kg for asphyxiation to be a concern, which is more than thirty times greater than the maximum charge size indicated by the submitter for trucks (i.e., 5 kg ).

• As shown under Threshold Analysis 1b, the charge size of the R

- 513A refrigerated trailer unit in a 100 m 3 container would have to be at least 190 kg for asphyxiation to be a concern, which is approximately thirteen times greater than the maximum charge siz e indicated by the submitter for trailers (i.e., 15 kg).

• In order for a risk of asphyxiation to occur from the release of a 5 kg refrigerated truck unit , the volume of the container would have to be approximately 2.6 m 3 (93 ft 3 ), or approximately thirty ti mes smaller than the typical truck size indicated by the submitter (see Threshold Analysis 2a).

• Using the largest charge size of 15 kg for refrigerated trailers , as shown under Threshold Analysis 2b, the volume of the container would have to be approximate ly 7.9 m 3 ( 280 ft 3 ) , or approximately thirteen times smaller than the typical trailer container size indicated by the submitter for asphyxiation to be of concern. Based on the modeling results and threshold analysis in Table 7 , EPA does n ot believe that the use of R

513A in refrigerated transport poses a significant risk of asphyxiation or imp aired coordination to personnel, provided systems are installed in appropriate spaces according to guidelines from the manufacturer and the SDS for R

- 513 A

. 

### 9. END

- US E EXPOSURE ASSESSMENT This section presents estimates of potential end

- user exposures to R

- 513A and each of its chemical constituents in the event of a catastrophic release from the proposed substitute’s use in refrigerated transport units

. An end

- use exposure analysis was performed to examine potential catastrophic releases of R

- 513A under the scenario outlined in Section 5. This end

- use exposure assessment examines a scenario in which personnel are located inside the refrigerated transport unit containing goods; such scenarios are expected to occur while the container doors are open. When the container door s are opened, a stack effect exists from the presence of the denser, cold air coming into contact with the warm, moist air outside. This effect will cause the colder air to flow outside of the container and become replaced by the warm, outside air through infil tration. Therefore, EPA expects that if a release of the proposed substitute occurs while personnel are present inside the refrigerated transport container (e.g., during loading and unloading of refrigerated goods), the container doors would be open, incre asing the air exchange rate inside of the unit and also resulting in diffusion of any R

- 513A to flow towards the outside of the container. To simulate a worst

- case scenario, the catastrophic release of the entire charge of the unit into the refrigerated co ntainer was modeled. The estimated exposures are conservative, as the analysis assumes that a catastrophic release occurs while the refrigerated transport container doors are closed and also does not consider other variables that would reduce the levels to which individuals would be exposed. The analysis
w as undertaken to determine the 15

- minute exposures for R

- 513A , which were then compared to the standard toxicity limits presented in Table 5 to assess the risk to end

- users. Because HFO

- 1234 yf is present i n larger concentrations and because it has a lower exposure limit than HFC

- 134a, Table s 8 a and 8b only display exposures for HFO

- 1234 yf , the component with greater potential concerns

. Modeling results are presented in Table 8a.Final

— July 2, 2015 9 Table 8 a . End

- Use Exposure Assessment for HFO

- 1234 yf Component a Refrigerated

Transport Containers Scenario Charge Size (kg) Container Size (m 3 ) Component 15

- min TWA End

- Use Exposure

(ppm) Exposure Limit (ppm) b Short

- term (15

- min) Acute Toxicity
Trucks Worst

- Case Scenario 1a 2 78 HFO

- 1234yf 2, 6 90 1,500 c 10 1 ,000 Worst

- Case Scenario 1b 5 6, 720
Trailers Worst

- Case Scenario 1c 7 100 7, 4 60 Worst

- Case Scenario 1d 15 15, 9 90 Bold font indicates modeling results.

a Cells highlighted in green are the scenarios in which the charge and container sizes evaluated in this risk screen are accept able given various modeling assumptions

. b See Table 5 for more information

c EPA

- derived STEL (see Table 5). Under the worst

- case scenarios described in Section 5 for refrigerated transport systems in trucks and trailers, catastrophic releases of the typical and maximum charge sizes of R

- 513A were modeled

. Although the exposure estimates for the reasonable worst

- case scenarios exceed the STEL for the HFO

1234yf component (i.e., 1 ,500 ppm) (see Table 8 a ), the STEL is a conservatively

- derived exposure limit that is intended to protect workers in an occupationa l setting in which they are exposed to these chemicals on a daily basis

. The STEL values do not represent limits for a single exposure in a lifetime. These modeled exposures are one

- time exposures following a catastrophic release of refrigerant so exceedan ces of the STEL values do not necessarily indicate a significant risk of harm to end

- users. The effect of a one

time exposure can be more accurately evaluated by comparing the modeled exposure concentrations to the ATEL, which is a limit intended to reduce the risks of acute toxicity hazards in normally occupied, enclosed spaces according to ASHRAE Standard 34 (see Table 6). All of the modeled exposure estimates are significantly lower than the ATEL of 10 1 ,000 ppm for HFO

- 1234 yf . Furthermore, the estimated exposures for R

- 513A in each of these scenarios are also significantly lower than the RCL for R

- 513A (i.e., 72,000 ppm). B ecause the modeling was done using a conservative worst

- case scenario where the refrigerated transport container door s are closed , and because normally personnel would be exposed in a situation where the container door s are open with significantly higher ventilation levels, personnel exposure to the proposed substitute at end

- use is not expected to reach the modeled concentrations s hown in Table 8a. Therefore, end

- use exposure is not considered to be a significant risk. A threshold analysis was performed to determine the combinations of charge sizes and container sizes with a 25 m 3 /hr ventilation rate that would avoid end

- use exposu res above the STEL for HFO

- 1234 yf (i.e., 1 , 500 ppm). The results from the threshold analyses are used to establish general guidelines for choosing an effective container size and charge size such that the use of R

- 513A in refrigerated transport units does not present risk to end

- users or servicing technicians. The se estimated charge and container sizes are fairly conservative as the analysis does not consider open container doors and other variables that would reduce the levels to which individuals would be exposed. The results of the threshold analyses are presented in Table 8b. Table 8b. End

- Use Exposure Threshold Analysis for HFO

- 1234yf Component Refrigerated

Transport Container Scenario Charge Size (kg) Container Size (m 3 ) End

- Use Exposure (ppm)

HFO

- 1234yf Trucks Threshold Analysis 1a: Charge Size 1

. 1 78 ( 2,760 ft 3 )
1,500 a Trailers Threshold Analysis 1b : Charge Size 1. 4 100 (3,530 ft 3 ) Trucks Threshold Analysis 2a : Container Size 5 370 ( 1 3

, 0

1 0 ft 3 ) Trailers Threshold Analysis 2b : Container Size 15 1, 1 2 0 (

3

9

, 40 0 ft 3 ) Bold font indicates modeling results.

a EPA

- derived STEL (see Table 5).Final

— July 2, 2015 10 Based on these results, for a minimum container volume of 78 m 3 ( 2,760 ft 3 ) , end

- use exposure above the STEL would not be a concern as long as the charge size does not exceed 1

. 1 kg (see Threshold Analysis 1 a in Table 8b ) and for the maximum proposed charge sizes in trucks and trailers (i.e. , 5 and 15 kg , respectively ) exposure would not be a concern if the refrigeration unit is installed in a co ntainer o f effective volume of at least 370 m 3 ( 1 3 , 0 1 0 ft 3 ) and 1, 1 2 0 m 3 ( 3 9 , 40 0 ft 3 ), respectively (see Threshold Analyses 2a and 2b in Table 8b ). As shown in Table 8b, these recommended minimum container sizes vary in direct correlation with charge size, and are more conservative than the intended charge sizes provided by the submitter. However, these modeling results presented in Table 8a and 8b ar e derived using the STEL (i.e., 1,500 ppm), which is the most conservative short

- term exposure limit for HFO

- 1234 yf and reflect conditions that are assumed to be a worst

- case scenario, as described in Section 5

. Infiltration rates through the opening of a refrigerated truck container have been measured to be approximately 2,520 m 3 /hr, which is roughly 100 times the ventilation rates used in the threshold analyses (Bonjour et. al 2011). A s previously discussed, EPA expects the refrigerated container door s to be open while personnel are present inside the container at end

- use, increasing the air exchange rate inside of the unit and also encouraging any R

- 513A to flow towards the outside air. Therefore, under a reasonable worst

- case scenario where the refrigera ted container doors are open, the exposures shown in the modeling results (see Tables 8a and 8b) are unlikely. Because refrigerated transport units using the proposed substitute were modeled using a conservative, worst

- case scenario where the refriger ated transport container doors are closed, personnel exposure above the proposed substitute’s STEL is unlikely. However, these potential exceedances emphasize the importance associated with proper equipment use, employment of engineering controls to limit relea ses and/or exposures, and the need for workforce training. To prevent exposure and reduce the risk of acute toxicity hazards during larger releases in any location where an R

- 513A system is installed, EPA recommends that the proposed RCL for R

- 513A (i.e., 72,000 ppm or 320 g/m 3 ) and the ATEL for the individual components (i.e., 101 , 000 ppm for HFO

- 1234 yf and 50,000 ppm for HFC

- 134a) are not exceeded and that proper leak protection devices are in place. In addition, EPA recommends the installation of refrige rant detection monitors on both ends of the refrigerated container, especially near the refrigeration system unit, and ensure the doors to the refrigerated container are open while personnel are inside. EPA also recommends that warning labels are present i n the refrigerated transport container indicating that R

- 513A refrigerant is in use and can cause suffocation, injury, or death. An example of this warning label would read: “WARNING: R

- 513A gas can cause injury or death. Ventilate the area before entering. A high R

- 513A concentration can occur in this area and can cause suffocation.” Training materials and an operations manual describing procedures for proper use of the equipment , safety gui delines for handling R

- 513A , and safety training is required for all personnel operating and servicing the refrigerated transport unit

. These procedures and guidelines should be acknowledged and followed to mitigate exposure in case of R

- 513A leakage in re frigerated transport units

. 

### 10. OCCUPATIONAL EXPOSURE ASSESSMENT
This section assesses potential exposures to workers during manufacture, charging and servicing, and disposal of R

- 513A refrigerated transport equipment

. To ensure that use of the proposed substitute in refrigerated transport does not pose an unacceptable risk to workers during charging, servicing, and disposal, occupational exposure modeling was performed using a box

- model approach

. For a detailed description of t he methodology used for thi s screening assessment , the reader is referred to the occupational exposure and hazard analysis described in Chapter 5 of the Background Document

. Estimates of refrigerant release per event for various release scenarios were obtained from the Vintaging Model. 6 To determine the estimated level of occupational exposure for a constituent in a blend, the total

6 ICF International maintains the Vintaging Model for EPA in order to simulate the aggregate impacts of the ODS phaseout on theFinal

— July 2, 2015 11 anticipated release rate of the refrigerant is multiplied by the weight percent composition of each compound in the blend. For charging, servicing, an d disposal activities, t he release rate per event was multiplied by the number of events estimated to occur over a workday. D uring charging and servicing , t he release per event was conservatively assumed to range between 0.6 percent and 8 percent of the eq uipment charge, respectively

. For equipment charging and servicing, the number of events per workday was assumed to equal the maximum number of units anticipated to be serviced in one day (i.e., eight units divided by eight hours per workday for refrigera ted transport units in trucks and trailers) (see Section 10.2). For equipment disposal of refrigerated truck and trailer systems, the release per event was conservatively assumed to be 100 percent of the equipment charge (representing a catastrophic releas e). It was assumed that 10 units are disposed of during an 8

- hour work day; however, it was assumed that of the ten units, only the last unit per workday would experience the catastrophic release (i.e., 100 percent). The remaining 9 units were assumed to r elease only an incidental amount of refrigerant (i.e., 1 percent per unit) from the connecting and disconnecting of lines, as it is likely that if a worker was exposed to the entire charge of a system during disposal activities, they would immediately stop working, clear the area until all refrigerant has been removed from the space (e.g., through ventilation), and adhere to the exposure procedures recommended in the SDS for the proposed substitute (see Section 10.3). The modeled exposure concentrations we re compared to STELs at charging and servicing and long

- term exposure limits at disposal. Similar to the end

- use exposure assessment, Table s 9 and 1 0 only present exposures for HFO

- 1234 yf , the component with greater potential concerns.

10.1 Occupational Exposure at Manufacture During manufacture of the components and blending of R

- 513A , the SDS for both HFC

- 134a and HFO

1234yf should be referenced and proper engineering controls and PPE used. Refrigerant quality control testing may also result in release of de minimus quantities of refrigerant, which would typically be to exhaust ducts or fume hoods. To prevent significant exposure if such leaks occur, e ngineering controls should be used, including normal and local ventilation (e.g., ch emical hoods) and vapor

- in

- air detection systems for standard manufacturing procedures so workers can avoid physical contact with the refrigerant and to achieve emission control. In general, use of PPE consistent with OSHA guidelines is recommended, such a s respiratory protection (including a self

- contained breathing apparatus [SCBA] in case of insufficient ventilation), tightly sealed goggles, and protective gloves (OSHA 1994). In addition, as for other halogenated refrigerants, there is a risk of generat ion of toxic degradation products such as hydrogen fluoride and hydrogen chloride if HF C

- 134a or HFO

- 1234 yf are exposed to high temperatures or fire. Other reaction products such as carbon dioxide might also be present. Containers should be stored in cool, dry conditions (maximum storage temperature should be 40 ° C) in well

- sealed receptacles and should not be allowed to contact open flames, glowing metal surfaces, or electrical heating elements. EPA believes that when proper handling and disposal guidelines are followed , in accordance with both good industrial hygiene and manufacturing practices and the SDS for R

- 513A and its components , there is no significant risk to workers during the manufacture of R

- 513A

. 10

. 2 Occupation al Exposure at Charging and Servicing

use and emissions of various ODS and their substitutes over a period of several years across 60 different end

- uses. The model tr acks the use and emissions of various compounds for the annual vintages of new equipment that enter service in each end

- use. The vintage of each type of equipment determines such factors as leak rate, charge size, number of units in operation, and th e ini tial ODS substance that the equipment contained.Final

— July 2, 2015 12 Charging and servicing activities for refrigerated transport units are not expected to result in significant worker exposure when certified technicians follow the procedures outlined in the R

- 513A SDS and maintenance manual, undergo proper traini ng, and wear appropriate PPE (e.g., gloves and safety glasses). Nevertheless, the potential occupational exposure during servicing was analyzed. The maximum 15

- minute TWA exposure s for each R

- 513A constituent were estimated for the charging and servicing exposure scenario and compared to the ir respective STELs (see Table 9 )

. Because HFO

- 1234 yf is present in larger concentrations and because it has a lower exposure limit than HFC

- 134a, Table 9 only presents exposures for HFO

- 1234 yf , the component with great er potential concerns.

Table 9 . Occupational Risk Assessment at Charging and Servicing for HFO

- 1234 yf Component a

Equipment Scenario Charge Size (kg) Component 15

- minute TWA Occupational Exposure (ppm) 15

- min Short

Term Exposure Limits (ppm) Charging (0.6% release) Servicing (8% release)
Trucks Reasonable Worst

- Case Scenario 1a 2
HFO

- 1234yf 6 75
1, 500 b Reasonable Worst

- Case Scenario 1b 5 16 21 0
Trailers Reasonable Worst

- Case Scenario 1c 7 22 300 Reasonable Worst

- Case Scenario 1d 15 48 6 40 Bold font indicates modeling results.

a Cells highlighted in green are the scenarios with acceptable exposure levels given various modeling assumption options

. b EPA

- derived STEL (see Table 5 ) The anticipated 15

- minute TWA exposures for the HFO

- 1234 yf component of R

- 513A are not anticipated to exceed its STEL (i.e., 1,500 ppm) for all scenarios (see Table 9). In addition, t he estimated exposures were derived using conservative assumptions, and do not take into account the use of ventilation o r PPE. These types of systems are typically serviced by trained personnel using proper industrial hygiene techniques and using proper engineering controls (e.g., local ventilation, refrigerant detectors, and alarm systems). Thus, EPA does not believe that charging or servicing of refrigerated transport units containing R

- 513A present a significant concern to workers.

10.3 Occupational Exposure at Disposal Disposal of R

- 513A in refrigerated transport units is expected to occur with limited frequency (approximately ten disposal event s per day) at disposal facilities with limited duration of exposure to the installed refrigerant. Typically, p otential exposures to the refrigerant during recovery and disposal are expected to occur during activi ties related to decommissioning refrigeration systems (e.g., attaching of hoses associated with draining or otherwise discharging of refrigerant from the refrigeration units into cylinders) and would be similar to those during servicing, because similar re frigerant charging and/or recovery equipment would be used (see Section 10.2 and Table 9 for information and modeling results related to exposure during servicing activities). As shown in Table 9 in Section 10.2, exposures during servicing (and therefore during typical disposal activities) are not anticipated to present a significant concern for workers. To model a worst

- case scenario during disposal, it was assumed that of the ten disposal events, nine units are properly disposed of with only incidental r eleases of refrigerant (i.e., 1 percent per unit) followed by the disposal of one unit that results in a catastrophic release of refrigerant (i.e., 100 percent of the charge). Table 1 0 presents the maximum estimated 8

- hour TWA occupational exposure levels for the constituents of R

- 513 A during disposal

. Because HFO

- 1234 yf is present in larger concentrations and because it has a lower exposure limit than HFC

- 134a, Table 1 0 only presents the maximum estimated 8

- hour TWA occupational exposure levels for HFO

- 1234 yf , the component with greater potential concerns.Final

— July 2, 2015 13 Table 1 0 . Occupational Risk Assessment at Disposal for HFO

- 1234 yf Component a
Equipment Scenario Maximum Charge Size (kg) Component 8

- hour TWA Occupational Exposure (ppm) 8

- Hour Long Term Exposure

Limits (ppm)
Trucks Reasonable Worst

- Case Scenario 1a 2
HFO

- 1234yf 170
500 b Reasonable Worst

- Case Scenario 1b 5 420
Trailers Reasonable Worst

- Case Scenario 1c 7 580 Reasonable Worst

- Case Scenario 1d 15 1,250 Bold font indicates modeling results.

a Cells highlighted in green are the scenarios with acceptable exposure levels given various modeling assumption options

. b 8

- hour WEEL The results in Table 1 0 indicate that long

- term (8

- hour) worker exposure concentration of the HFO

- 1234 yf component of R

- 513A is not likely to exceed its WEEL (i.e. , 500 ppm) in trucks ; however, the reasonable worst

- case disposal scenarios for trailer units of 7 and 15 kg charge size could potentially exceed the WEEL for HFO

- 1234yf. Although the modeling indicates that the worse

- case disposal scenario could exceed the WEEL for HFO

- 1234 yf, the estimated exposures were derived using conservative assumptions (e.g., no mechanical or local exhaust ventilation ). These types of systems are t ypically disposed of by Section 608

- certified personnel using proper industrial hygiene techniques to maximize recovery efficiency and limit releases, and there are already established standards of practice and training requirements that apply to fluorinat ed refrigerants to reduce exposures (and would therefore extend to R

513A systems)

. I t is also unlikely that workers would be exposed to the unrecoverable portion of refrigerant during the recovery process , and therefore anticipated exposures would be app roximately ten percent lower . For example, some of the refrigerant would likely be dissolved in the refrigerant oil (which would be drawn out and separated from the recovered refrigerant) or trapped within deeper parts of the refrigeration circuit (e.g., t he accumulator or receiver) and wouldn’t be released until the system is actually dismantled later on in the disposal process (Oko

- Recherche 2003). Because anticipated occupational exposures could exceed the exposure limit for HFO

- 1234 yf for some of the d isposal release scenarios (i.e., Reasonable Worst

- Case Scenarios 1 c and 1d ) for refrigerated transport applications, the recommendations for proper engineering controls and PPE in the SDS for R

- 513A should be followed. Adequate ventilation should always be established during any use, handling, or storage of R

513A

. If recovery and disposal is taking place in an enclosed space without any mechanical ventilation, facilities should be cleared of non

- essential personnel and technicians should wear a SCBA and other appropriate protective equipment. Engineering controls should include vapor

- in air detection systems and local exhaust ventilation during use of R

- 513A to prevent dispersion throughout the workplace. In addition, an eye wash and safety shower should be near the manufacturing facility and locations where R

- 513A is stored and ready for use. In general, use of PPE is recommended, such as splash goggles, m echanical resistance gloves (e.g., oil

repellent or thermal resist ance gloves) when handling cylinders and recovery equipment and chemically

resistant gloves when handling the gas mixture (e.g., butyl rubber, chlorinated polyethylene, or neoprene). The installation of signage which warns room occupants to remain standing (as higher concentrations are likely to accumulate near the floor) , not to enter recessed parts of the facility (e.g., maintenance crawl spaces and below grade service areas) , and exit the facility immediately should they hear the refrigerant detector ala rm and/or smell the leaked refrigerant would further minimize toxicity risks. EPA believes that if proper handling and disposal guidelines are followed , in accordance with good industrial hygiene and manufacturing practices and the SDS for R

- 513A , there is no significant risk to workers during the manufacturing, installation, servicing, and disposal of R

- 513A in refrigerated transport units.


### 11

. GENERAL POPULATION EXPOSURE ASSESSMENTFinal

— July 2, 2015 14 R

- 513A is not expected to cause a significant risk to human health in th e general population when manufactured for use and used as a refrigerant in refrigerated transport units

. The proposed substitute will be manufactured in a closed process and is proposed for use in closed systems ; thus, significant releases are not anticip ated. At room temperature, R

- 513A is a gas and, therefore, releases to ground or surface water are not anticipated, as R

- 513A is anticipated to dissipate into the atmosphere upon release to outside air (i.e., because natural ventilation rates would be higher and there is no enclosed space to maintain a high concentration of R

- 513A ). Should air releases during manufacturing operat ions occur, engineering controls should be used (e.g. , carbon absorption scrubbers) to collect R

- 513A and prevent the release of R

- 513A to the atmosphere. EPA believes that by using proper engineering controls and by following disposal and containment reco mmendations outlined in the proposed substitute’s SDS and this risk screen , exposure to R

- 513A is not expected to pose a significant toxicity risk to the general population.Final

— July 2, 2015 15 

### 12

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ANSI/ASHRAE. 2010a. S tandard 15: Safety Standard for Refrigeration Systems. American Society of Heating, Refrigerating and Air

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392_DucoulombierSartreBonjour_revised_final.pdf Brecht, P., Hinsch, T., Kader, A., and Thompson, J. 2000. Marine container transport of chilled perishable produce

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- pdf/truckloadequipmentguide.pdf. DuPont Fluoroproducts. 2014. Opteon XP ® 10 for Use as a Refrigerant. Significant New Alternatives Policy Program Submission to the United States Environmental Protecti on Agency. August 2014. Forster, P., V. Ramaswamy, P. Artaxo, T. Berntsen, R. Betts, D.W. Fahey, J. Haywood, J. Lean, D.C. Lowe, G. Myhre, J. Nganga, R. Prinn, G. Raga, M. Schulz and R. Van Dorland. 2007. Changes in Atmospheric Constituents and in Radiati ve Forcing. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. Gallagher, Glenn, Tao Zhan, Ying

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gas Emissions in California: Comparison of Ambient

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- Hypoxic Atmospheres Conference. Stephanie Skaggs prepared the proceedings of the conference held May 22, 1997 in New London, CT.Final

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- Recherche and Ecofys. 2003. “Establis hing the Leakage Rates of Mobile Air Condi tioners”. Available online at: http://www.oekorecherche.de/sites/default/files/pub likationen/leakage_rates_0.pdf OSHA. 2004. “Safety and Health Topics: Isobutane.” Februa ry 2004. Available online at: http://www.osha.gov/dts/chemi calsampling/data/CH_247840.html Papadimitriou, V., R.K. Talukdar, R.W. Portmann, A.R. Ravishankara, and J.B. Burkholder. 2007. CF3CF=CH2 and (Z)

- CF3CF=CHF: Temperature dependent OH rate coefficients and global warming potential s. Physical Chemistry Chemical Physics. 9: 1

- 13. United Nations Environmental Programme. 2010. “2010 Report of the Refrigeration, Air Conditioning and Heat Pumps Technical Options Committee (RTOC) 2006 Assessment. Available online at: http://acd

ext.gsfc.n asa.gov/Documents/O3_Assessments/Docs/WMO_2010/2010assessment/RTOC_2010_Assess ment_Report.pdf > U.S. EPA. 2012. Acute Exposure Guidelines (AEGLs) Definitions. Available online at: http://www.epa.gov/oppt/aegl/pubs/define.htm

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. 1994. Significant New Alternatives Policy Technical Background Document: Risk Screen on the Use of Substitutes for Class I Ozone

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- Report No. 52, 51 6 pp., Gene va, Switzerland

.